1. Field of the Invention
The present invention relates to a transistor protection circuit for protecting a transistor of a power electronics circuit and the like.
2. Related Background Art
There is designed a protection circuit for protecting a transistor of a power electronics circuit when an abnormal operation occurs in the transistor (e.g., the occurrence of overcurrent, overvoltage, high temperature). Japanese Patent Application Publication No. 2008-141841 discloses an overcurrent protection circuit that restricts the flow of current in a voltage-driven transistor of an inverter. When it is detected that an overcurrent flows through a transistor SW, this overcurrent protection circuit 40 gradually lowers a voltage to be applied to a gate terminal of the transistor SW, by turning the transistor of a soft interruption circuit 49 ON, and then soft-interrupts the transistor SW. This soft interruption can prevent an excessive surge voltage from occurring during the short circuit.
In addition, when performing the soft interruption, the overcurrent protection circuit 40 causes a drive circuit 30 for driving the transistor SW to stop supplying voltage to the gate terminal of the transistor SW. Specifically, the drive circuit 30 is caused to turn ON a transistor 31p for supplying a high-potential-side voltage and a transistor 31n for supplying a low-potential-side voltage.